The present invention relates to a computer system. More particularly, the invention relates to a computer system capable of operating multiple virtual machines.
A virtual machine allows single hardware to provide multiple computer systems, namely, a highly reliable, real-time computer system such as a control system and a high-performance computer system for audiovisual processing.
The virtual machine includes virtual components such as a virtual central processing unit (CPU), virtualized physical memory, and a virtual IO device. The virtual machine implements the virtual components by allowing them to be dedicated to or share physical components (physical CPU, physical memory, and physical IO device).
An abnormal state due to a device (hereinafter referred to as IO) error may occur under an environment that uses the virtual machine. For example, the method proposed in patent document 1 detects the error and prevent an abnormal state from expanding. The method provides an association table to associate IOs used for operating systems (OS's) and a means to detect IO errors, specifies a virtual machine from the association table corresponding to an error, if any, and stops only the specified virtual machine.
A multithreaded processor is provided for computer systems such as control systems that require highly real-time capability. The multithreaded processor divides the processor usage time into predetermined time intervals or instructions and performs multiple processes by switching them. Since processes are switched during execution, the multithreaded processor can reliably ensure the time for real-time processing while performing audiovisual multimedia processes. For example, the method proposed in patent document 2 accelerates specific processes. The method uses multiple scheduling registers for a scheduling process of the multithreaded processor and changes ratios of threads available for normal operation and an interrupt process.
For example, the method proposed in patent document 3 generates an interrupt via a bus bridge if an IO error causes an abnormal state. When an initialization instruction is issued to the OS or a device driver, the software such as the OS or the device driver reinitializes the communication control portion.
Patent Document 1: Japanese Unexamined Patent Publication No. 2007-323142
Patent Document 2: Japanese Unexamined Patent Publication No. 2010-86129
Patent Document 3: Japanese Unexamined Patent Publication No. 2003-330817